Wednesday, November 7, 2012

Probiotics


Probiotics and IBD


The human intestines contain approximately 100 trillion (yes, that's 100,000,000,000,000) bacterial cells from up to 1,000 species.  Bacteria play a definitive role in gastrointestinal health, as anyone who has encountered a bad strain of clostridum difficile (C. Diff) or escherichia coli (E. Coli) can attest.  Bacteria also play a positive role in the digestive system - the standard flora keep out bad microbes and assist in digestion of certain categories of food, including carbohydrates.  The role of bacteria is so critical, doctors are experimenting with fecal transplants (the topic of a future posting) to treat IBD and other conditions.

Probiotics are bacteria (or yeasts) that are widely believed (and have been shown) to have a positive impact on intestinal operations. There are many different bacterial strains marketed as probiotics, but the two most common are Lactobacillus (and other lactic acid bacteria or LAB) and several members of the Bifidobacterium family.  They  are both acid-resistant and can tolerate a fairly low pH, allowing them to successfully transit the stomach.  Lactobacillus is commercially used for fermentation, most commonly in the product of active yogurt cultures.

Probiotics have been shown to have some positive effects in clinical trials in controlling diarrhea (1) caused by antibiotics.  Because Cipro and Flagyl are common IBD treatments for everything from C. Diff to closing of fistulae, this shows promise as an adjunct therapy.  The effect size isn't great and there is no consistency in what strains to use (though LAB strains were the most common), but there were very few adverse effects.  Probiotics come in two primary forms - as part of incidental intake in food consumption or as a dietary supplement. Based on the higher quality studies reviewed, there doesn't appear to be any need to use specific supplements - fermented milk and yogurt showed similar efficacy.

Unfortunately, the news for long term use of probiotics in the maintenance of remission in both Crohns and UC is not well supported.  The latest meta-analyses show no statistically significant benefit for maintaining remission in either Crohns or UC (2) and conclude that, at present, there is no clinical reason to recommend them as a therapy.  The current research isn't overly extensive, however, and the door is open for better, more comprehensive studies in this area.

Outside of the supplement arena, the main food containing probiotics, yogurt, has many varieties and quite a few known benefits.  It is a well documented source of protein, vitamins B6 and B12, calcium, and riboflavin.  Additionally, it can sometimes be better tolerated than an equivalent amount of milk due to the breakdown of lactose in the souring process.  It can be eaten alone, used as a sauce (e.g. tzatziki) or used as a substitute for eggs when making breaded dishes (give it a try!)

Bottom Line


  • Probiotic supplements have shown no benefit for long term use in Crohns and UC to date in large, well-formed studies.
  • Consumption of yogurt and other probiotic-containing foods has general health benefits and minimal side effects.
  • Probiotic use in the treatment of antibiotic-related diarrhea has reduced the frequency and duration of symptoms.  Consumption of yogurt or fermented milk as an adjunct therapy should be considered for acute cases.
(1)  Probiotics for the Prevention and Treatment of Antibiotic-Associated Diarrhea: A Systematic Review and Meta-analysis, Susanne Hempel, PhD; Sydne J. Newberry, PhD; Alicia R. Maher, MD; Zhen Wang, PhD; Jeremy N. V. Miles, PhD; Roberta Shanman, MS; Breanne Johnsen, BS; Paul G. Shekelle, MD, PhD, JAMA 2012

(2)  (Probiotics for maintenance of remission in ulcerative colitis, Naidoo K, Gordon M, Fagbemi AO, Thomas AG, Akobeng AK, Cochrane Review 2011 and Probiotics for maintenance of remission in Crohn's disease, Rolfe VE, Fortun PJ, Hawkey CJ, Bath-Hextall FJ, Cochrane Review 2008

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